1. Field of the Invention
The invention relates to semiconductor processing, and more particularly to formation of contacts in compound semiconductor devices.
2. Description of the Related Art
Group III-V semiconductor devices such as diodes, heterojunction bipolar transistors (HBTs) and HEMTs require accurate lithographic registration of outer and inner contacts edges during their fabrication. To maintain good Ohmic contact resistance, registration must be approximately 20% of the contact width. As state-of-the art Group III-V processes are developed that allow sub-200 nm features, such lithographic registration accuracies become more difficult.
A need continues to exist to improve dimension registration of outer and inner contact edges in Group III-V semiconductor devices as their features become smaller.